login
A221051
The hyper-Wiener index of the nanostar dendrimer D_1[n], defined pictorially in the Eslahchi et al. reference.
1
71, 3696, 63950, 688090, 5703410, 40217250, 254522114, 1492368834, 8272324418, 43936883266, 225705715778, 1128962528322, 5525679156290, 26563127958594, 125778392431682, 587953338416194, 2718115098721346, 12445431340858434, 56504646938393666
OFFSET
0,1
REFERENCES
Ch. Eslahchi, S. Alikhani, M. H. Akhbari, Hosoya polynomial of an infinite family of dendrimer nanostar, Iranian J. Math. Chem. 2 (2011) 71-79.
FORMULA
a(n) = -958+2^n*(896*n^2-2904*n-19861)+4^n*(3136*n^2-11928*n+20890). Theorem 5 of the Eslahchi et al. paper contains a less explicit formula for the hyper-Wiener index.
G.f.: (71+2347*x+4376*x^2-17716*x^3-17696*x^4+2752*x^5)/((1-x)*(1-2*x)^3*(1-4*x)^3). - Bruno Berselli, Dec 30 2012
MAPLE
a := proc (n) options operator, arrow: -958+2^n*(896*n^2-2904*n-19861)+4^n*(3136*n^2-11928*n+20890) end proc: seq(a(n), n = 0 .. 18);
CROSSREFS
Cf. A221050.
Sequence in context: A332665 A017734 A263248 * A239718 A279904 A115447
KEYWORD
nonn,easy
AUTHOR
Emeric Deutsch, Dec 30 2012
STATUS
approved